Dental restorations generally comprise a metal core or framework to which porcelain is bonded on the visible surfaces for esthetic reasons. For many years gold has been the basic structural metal for preparing the core or framework. However, because of the high cost of gold, many attempts have been made to devise non-precious metal alloys which could be used in place of gold. Such compositions are illustrated, for example, by U.S. Pat. Nos. 1,736,053; 2,089,587; 2,156,757; 2,134,423; 2,162,252; 2,631,095; 3,121,629; 3,464,817; 3,544,315; 3,685,115; 3,716,418; 3,761,728; and 3,834,024; and in standard dental literature such as Skinner and Phillips, "THE SCIENCE OF DENTAL MATERIALS," p. 582, Sixth edition, W. B. Saunders Company, Philadelphia and London, 1967 and Morrey and Nelson, "DENTAL SCIENCES HANDBOOK," p. 168, American Dental Association and National Institute of Dental Research, U.S. Government Printing Office, Washington, D.C., 1970. Suitable alloys are typically nickel or cobalt-based alloys, particularly, nickel-chromium alloys.
This invention is directed to a bonding agent and to a method for bonding dental porcelain to a nickel-containing non-precious metal alloy framework. When dental porcelain is bonded to the metal framework using the bonding agents of this invention, a strong bond is formed which is able to resist separation of the porcelain under far greater stresses than in the absence of bonding agent. Moreover, the bonding agents of this invention can be used under less critical conditions than prior, similar bonding agents.